Photographic printing apparatus



5.1... HERS H PHOTOGRAPHIC PRINTING APPARATUS "scpt. 24, 1963 Fi'ied Feb. 6. 1961 5 Sheets-Sheet 1 INVENTOR, SEYMOUR L. HERSH ATTORNEY.

S. L. HERSH PHOTOGRAPHIC PRINTING APPARATUS Sept. 24, 1963 3,104,602

Filed Feb. 6. 1961 5 Shets-Sheet 2 INVENTOR, SEYMOUR L. HERSH BYXWW W"? ATTORNEY.

' Sept. 24, 1963 s. HERSH PHOTOGRAPHIC PRINTING APPARATUS- 5 Sheets-Sheet 3 Filed Feb. 6. 1961 vdI I R, SEYMOUR L. ,Hsasw ATTORNEY.

Sept. 24, 1963 s.-1 HERSH 3,104,602

PHOTOGRAPHIC PRINTING APPARATUS Filed Feb. 6. 1961 s Sheets-Sheet 4 FIG.5

INVENTOR, SEYMOUR HERSH ATTORNEY.

Sept. 24, 1963 s. HERSH 3, 04, 02

PHOTOGRAPHIC PRINTING APPARATUS Filed Feb. 6. 1961 5 Sheets-Sheet 5 T gsi w-i 96 POWER SOURCE FIG. I l

|2l SOLUTION oo/- TEMPERATURE CONTROL CONVEYOR I02 DRIVE MOTOR |O2\ 2 I02 7 4| SUCTION FAN 99 99 MOTOR INVENTOR, SEYMOUR L. HERSH ATTORNEY.

United States Patent 3,104,602 PHOTOGRAPHIC PRINTING APPARATU Seymour L. Hersh, Monmouth County, N.J., assignor to the United States of America as represented by the Secretary of the Army Filed Feb. 6, 1961,,Ser. No. 87,505 1 Claim. (Cl. 95-77.5) (Granted under Title 35, US. Code (1952), see. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment of any royalty thereon.

This invention relates to a machine for handling and processing photograph-ically sensitized elements and particularly to the semiautomatic processing sequence including registering of an original such as a processed negative upon the surface of a sensitized sheet, exposing the sheet through the negative, and processing the exposed sheet.

Machines have been used heretofore for printing and processing photographic materials but have failed to provide the fast and eflicient technique oifered by the present invention wherein an exposing means is particularly devised for direct integration of its function with that of the subsequent single or multiple step chemical processing operations. The chemical processing operations are carried out upon a compact cylindrical device wherein the exposed sensitive sheets are presented successively to processing heads which apply a film of solution to the emulsion side of the sheet only. Thus the operation is completed without the use of multiple open trays in which the sheets are completely emersed and withdrawn. This latter operation is wasteful of space and solutions. Moreover when the sheets are so emersed, drying becomes a wasteful power and time consuming operation.

The mechanism of the invention provides a hollow glass cylinder rotated on its axis and having an elongated lamp therein. A guide platen facilitates the feeding of a sheet of printing paper and a negative registered in contact therewith into the printing section of the device where they are carried along between the periphery of the cylinder and a driven apron at the upper portion of the cylinder. While passing thru this conveying means the sheet is printed by the light emerging from a slot in a housing surrounding the lamp.

Immediately upon emerging from this conveyor means the negative and printing sheet separate and the sheet, continuing its movement, engages a second conveying .means having a second driven apron. The second apron may be an extension of the first mentioned apron. This apron is porous and engages the printing sheet to move it in a cylindrical path in contact with the cylinder and while so traveling the sheet encounters a plurality of processing units of special construction to be described hereinafter. Each unit has a small elongated outwardly open solution chamber extending across the print. When no print is present the chamber is open and a solution circulating pump of the vacuum type runs idly. When a print covers the open chambers and seals oil the vacuum leak, solution circulates in the chambers to process the print which is then conveyed to an infra red drying station.

The complete system which will subsequently be described provides perfectly coordinated handling and timing control of the negative and printing sheet at every instant while they are printed and during the chemical processing of the print.

It is a primary object of the invention to provide an apparatus for efficiently manipulating an individual negative or other subject to be printed together with a cut sheet of printing material registered therewith during its 2 exposure and subsequently during its chemical processing cycles.

A further object of the invention is to provide an apparatus for continuously moving a negative or other subject and a cut sheet or continuous strip of printing paper in register therewith thru a printing station and thru a series of processing stations without interruption.

A still further object of the invention is to provide apparatus for continuously moving an individual negative or other subject in register with a cut sheet of printing paper and automatically providing conditions of exposure and processing timing to provide desired characteristics in the end product.

A still further object of the invention is to provide a continuously operating photographic processing apparatus wherein the exposure of a sheet of printing material thru a registered negative or other subject is derived from a line source of illumination applied during its motion thru the exposing station of the apparatus and wherein processing solutions are applied in a film to the emulsion side of the sheet only while the sheet moves thru the chemical processing station.

A further object of the invention is to provide an apparatus for printing individual negatives or other subjects upon sheets of printing material wherein the processing solutions are applied to the sheets thru lateral slots in solution applying units while the sheets move thereover and the presence of the sheets covering the slots act to initiate the flow of solution at the slot.

ther objects and features of the invention will more fully appear from the following description and will be particularly pointed out in the claim.

To provide a better understanding of the invention it will be described in connection with the accompanying drawings wherein:

FIGURE 1 is a top plan view of the apparatus.

FIGURE 2 is a side elevation of the apparatus.

FIGURE 3 is a cross section on line 3-3 FIGURE 2.

FIGURE 4 is a cross section on line 44 FIGURE 1.

FIGURE 5 is an end elevation looking from the right.

FIGURE 6 is a bottom plan view of the suction chamber of the apparatus.

FIGURE 7 is a detail perspective view of one of the chemical solution applying units of the apparatus.

FIGURE 8 is a detail cross sectional view thru the apparatus at one of solution applying units.

FIGURE 9 is a detail cross section on line 9-9 FIG- URE 6.

FIGURE 10 is a partially schematic perspective view of the solution pumping system of the apparatus.

FIGURE 11 is circuit diagram showing the power supply connections for the apparatus.

The apparatus is compactly integrated and preferably its components are mounted upon a common base 10. The device executes photographic functions known as contact printing and chemical processing. A negative or other transparent subject of a similar sheet like form is placed in contact with a cut sheet of printing material of a size corresponding to the negative and both are held in register while they are fed into the left hand end of the apparatus where they are held together in close contact while they are fed thru an exposing station. It is also possible to use a continuous strip of printing material.

The elements of this station are supported by side frame plates 11 which are in turn supported on the base 10 by bnackets 12. The side plates are tied together at their top edges by a top plate 13. Between the side plates is rotatively mounted a hollow glass cylinder 14 which is supported and driven upon its axis by a plurality of rolls and conveyor aprons associated therewith. Certain of these rolls and their conveying means for the negative and printing paper. A

' single apron serving all of the components of the ap- 'roll 16 and at the same distance from the base 10.

An end-less belt or conveyor apron 18 travels around the rolls 1-5, 16 and 17. The apron may be of any suitable porous fabric or perforated plastic sheet material and travels around roll over the upper surface of roll 16, around roll 17 and back to the cylinder 14, where it 7 passes between the cylinder and roll 16, over a portion of the surface of the cylinder and back to the roll 15. The apron is as Wide as the Widest material being processed. Apair of rolls l9 and 20 over which travel a belt 21 are positioned at the bottom portion of the cylinder in such manner that the upper run of the belt 21 firmly engages the cylinder. The rolls 19 and 2d are supported in bearings received in the side plate ii and the shaft 22 of roll 20 is extended beyond the side plate to receive a driving worm gear 23. The gear 23 is engaged by a worm 24 which is journaled in bearings secured in the 7 side plate 11. A worm driving shaft 25 has a gear 26 receives a sprocket chain which in turn travels over sprockets 32 and 33 secured to the extended shafts of the rolls l5 and 16 which are thus also driven by the motor 7 As will appear more fully hereinafter the negative and the printing sheet are led into the point where the surface of the cylinder 14 meets apron 1-8. To assist such insertion a guide platen 34 having side flanges to engage the edges of the printing material is secured in position to direct the material to the bite between the cylinder associated apron also serves as 4 printing sheet against the apron 18 as it is fed to the processing station. The length of thevacuum chamber desirably should be suificient to support substantially the full length of the longest sheet of material to be processed or at least it should prolong the travel of the sheet sufficiently to permit the negative 34- to emerge [from between the cylinder M and theapron 1$ and fall by gravity into a container 43 directly below the vacuum chamber. a i 1 The'vacuum chamber has edge guides 44 and slotted guides '45 for accurately aligning the printing sheet. The I slotted guides completely'ernbrace the edges of sheet and precisely guide the forward edge thereof into the conveyor means on the chemical processing station. A deflecting lip 46 may be placed in the path of the sheet to fin-ally properly position its leading edge.

There are two cylindrical members within and concentric to the glass cylinder 14. The innermost cylinder 47 constitutes a lamp housing and a reflector made of sheet metal and supported in fixed position upon the common axis. Any suitable means may beused to support this lamp housing. As shown in FIGURE 3 short stud shafts 48 are secured to the side plates 11 and extend inward. The end closings 49 for the housing 47 are 14 and apron l8 and to insure proper registering of p the negative and printing sheet.

The registered negative and printing sheet are clamped between the apron 18 and the cylinder 14 and carried along with the driven cylinder to a position substantially at the horizontal tangent point of the cylinder where the negative 34 separates from the sensitive sheet 35 at which time the printing sheet is ted to the bottom surface 36 of an upwardly acting suction platen 37 which holds it in position in contact with the perforated apron while it is carried to the chemical processing station to be described hereinafter. The suction platen 37 is shown in FIGS. 4 and 6 and consists of a suction chamber 38 secured to the top plate 13 and positioned between the top and bottom runs of the apron 18 with its bottom face 36. in contact with the bottom run thereof. The face 36 7 extends completely across the apron and covers a substantial portion thereof along its length. The suction chamber is provided with a suction conduit 39 which is 7 connected to the suction port of a centrifugal blower it driven in anysuitable manner such as by the motor 41.

The bottom surface 36 of the suction chamber is provided with a plurality of slots 42 extending in the direction of travel of the apron 18 which itself is made of porous material or it may be made of thin plastic sheet material pertoratedwith small openings arranged to allow free passage of air thru the slots and the perforations. -Thus when a partial vacuum is created in the chamber 38 atmospheric pressure will act to hold the provided with collars fixed thereto .and having an aperture to receive the stud shafts. A set screw in the collar engages the shaft and holds the housing in fixed position.

Near the outerends of the housing 4'7 are secured supporting strips 50 upon which are mounted lamp sockets 51 within which are received a fluorescent'lamp 52 or other suitable light source extending lengthwise of the cylinder 14. Suitable electrical connections 53 supply power for the lamp. The inner surfaces of the housing are polished and all'other surfaces thereof desirably are finished in optical black. Exposure of the print is made thru a narrow slot 54 extending lengthwise of'the housing and at least as long as the lateral dimension of the printing material. Desirably means should be provided to vary the width of the slot 54 to adjust the quantity of light flux reaching the print. This may be done by providing a plurality of interchangeable plates 7 such as the plate 55 within which the slot is cut. The plates are screwed to the upper portion of the housing 47. The casing has an aperture therein slightly larger than the largest slot provided by the plates 55 to thus permit light from the lamp to reach the printing sheet 35. Desirably the housing 47 has an opening 56 which is normally closed by a cover 57. 'This opening provides for servicing the parts inside the housing including replacement of lamps and the like.

It is desirable in many instances to change the spectral quality of the light reaching the printing sheet 35 as for instance in the use of Varigam printing material. The contrast is varied in the well known manner by filtering the light with varicol-ored filters. This is accomplished by providing a cylindrical filter holding device 58- concentric with and outside of the housing-47. This holder is provided with a plurality of filter strips 59 of various colors suited to the printing procedure in use. The filter holder is pivotally mounted on the stud shafts 48 and an arrangement is provided to position a desired filter opposite the slot 54-. To accomplish this end a spring pressed pin 60 is supported upon the end plate of filter holder 58. The pin is provided with a knob 61 and projects thru the end plate to enter one of a series of aper tures in the end wall of the lamp housing 47. The apertures are spaced to divide the circumference of the member 58 into sections to accommodate the required numacting springs 65 which apply light pressure to the sheet I by contact of the discs therewith. The frame 64 is guided in suitable slots in the brackets in which the roll 17 is mounted.

The exposed cut sheet of material 35 is fed to and thru the processing station which supports, guides and transports, the sheet. Most of the components of this station are supported upon side frames in the form of circular discs 66 and 67 of metal such as aluminum of substantial thickness which are supported by brackets 68 secured to the base in parallel relation and a distance apart substantially equal to the width of the processed sheets.

Upon the periphery of each of the discs 66 and 67 are secured ball bearings 69 upon the outer movable member of which is received a tire 70 of resilient material such as rubber or plastic having an upstanding flange 71. The

'tires are so dimensioned that the flanges '71 are spaced a distance apart to freely receive and accurately guide the printing sheet and with the aid of the apron or belt 72 cause the sheet to be conveyed thru the processing station, and thence to the dryer to be described.

The apron 72 is guided and driven in its travel by a series of rolls. It is made of perforated plastic sheeting or porous fabric and is substantially the same width as the printing sheet. The apron passes around a roll 73 which rotates counter clockwise and is positioned to cause the apron 72 to engage the periphery of the tires 70 from where it continues clockwise around the discs 66 and 67 and thence at the bottom of the discs the apron extends horizontally to the left where it engages the roll 74 suitably supported upon the base 10. The apron then travels back toward the right passing over roll 75 pivoted in supports fastened to the base and rising substantially vertically to and over the rolls 76 and 77 and back to the roll 73. An additional roll 78 may be inserted at the bottom of the discs to provide better support for the apron as it leaves the discs.

It will be seen that the apparatus thus far described provides a complete conveyor system for the negative and printing sheet during the processing cycle. The apron 72 as it leaves the bottom portion of the chemical processing station carries the finished, but slightly damp print to a drying device 79 to be described and thence, to a receptacle 86 adjacent to the roll 74.

The rolls 73 and 77 are irotatively supported in a pair of brackets 81 secured to the side of discs 66 and 67 while the roll 76 is mounted in brackets 82 secured to the discs.

Suitable means is provided for driving the apron 72. As shown the shaft upon which the roll 75 pivots is extended and has fixed thereto a sprocket 83 over which a chain 84 passes. This chain in turn is driven by a sprocket 85 fixed to a shaft 86 rotatably supported in brackets secured to the base 10. The shaft 86 also has a worm gear 87 fixed thereon meshing with a worm 88 secured to the output shaft of speed changing unit 89 the input shaft of which is gear driven by the motor 30 the shaft of which is double ended. The change speed unit is supplied with means for changing its driving ratio and thus varying the speed of the apron 72. 7

Along the upper periphery of the chemical processing station are secured a plurality of processing units, 90 angularly spaced at a distance found to be most effective. These processing units may be arranged to perform a variety of processing operations. In the example illustrated the units are arranged to successively develop,

short stop, fix and wash the print. One of the processing units is shown in detail in FIG. 7. They may be made of any suitable corrosion resistant material such as Teflon or metal which is non-corrosive.

The units are secured between the side plates 66 and 67 in any suitable manner as by screws engaging their end faces. The units are provided with slots 91 which extend laterally across the path of the apron 72 and which constitute solution chambers of small liquid capacity which function to apply processing solutions to the emulsion of the printing sheet. The slots are positioned to present their open side tangential to the curve of the apron 72. As printing sheets are conveyed through the processing station by the apron they are caused to pass successively over the slots 91 and in doing so close the open side thereof. Each slot or chamber 91 is provided with ports 92 and 93 communicating with opposite ends of the slots. The ports are connected with a system, to be described hereinafter, for applying a constant flow of processing solution to the slots. The slots are relatively narrow and shallow and thus provide for rapid chnage of solution. Desirably a thin end wall is provided at each end of the slots 91. Fresh solution is thus constantly reaching the emulsion of the printing sheet as it passes thereover.

As shown in the drawings the body of the individual units 90 are substantially cylindrical. They may however be of any suitable conformation. It is also within the scope of the invention to provide a unitary member of Teflon or other non-corrosive material having slots therein for all of the processing steps. However the use of individual processing units permits adjustment of their position along the path of travel of the printing sheets whereby the timing of the processing steps may be varied. Such adjustments may be provided by forming circular slots 94 in and concentric to the periphery of the side plates 66 and 67. Within these slots are received the screws 95 serve as guiding means when the units are repositioned. Only the developing unit is shown as adjustable. The other units 90 may also be made adjustable in the same manner to still further regulate the time periods for various processing steps.

The processing solutions are supplied to the unit 90 from a plurality of tanks 96 which desirably may be at least partially received Within the space between the side plates 66 and 67. There are four such tanks shown in FIG. 4 and FIG. 10 closely spaced and secured to a supporting platform 97. The platform and the tanks extend thru the plate 67 to the right in FIG. 5 a substantial distance beyond the plate. The platform is secured to both plates 66 and 67 by brackets 98 or other suitable means. The elongated contour of the tanks provide a considerable capacity for solution and each tank is provided with an electric heater 99 projecting into the liquid within the tanks.

When it is desired to execute a very fast developing op eration the heaters maintain the solutions at a temperature elevated above room temperature and thus shorten the time cycle for processing prints or other photographic units.

At least one of the tanks is provided with a thermostatic control unit connected to a power source and having its controlled output connected to the heaters 99. As shown the first tank which is normally used for developing contains the control unit and has its sensing member emersed in the solution. The control 106 may be of conventional construction and has a manual adjustment for selecting the desired temperature. This first tank is longer than the others to accommodate the sensor of the control member.

Desirably the heater in each tank is provided with conventional double contact connectors 101.

Controlled power from the member 164) is fed to the heaters 99. Any one or all of the heaters may be rendered active by coupling power to the connectors 101 thru separate power leads 192. Any suitable means for feeding power to the heaters may however be used.

Desirably the shaft is provided with ball bearings received in the cover plate and platform.

The upper end of each drive shaft hassecured thereon a driving gear 106 which are interconnected by three idler gears 7 intermeshing therewith. The idler gears are rotatively mounted on vertical stud shafts secured in the platform 97. The center idler gear meshes withand is driven by a gear 108 rotatably mounted upon a shaft 109 fixed to the platform. The gear 108 has fixed thereto a second gear 110 which meshes with another gear 111 connected to one of a pair of miter gears 112. The gear 111 and one of the miter gears are axially coupled and rotate upon a stud shaft secured to the platform W. The

other miter gear is secured to the shaft of a motor 113 secured to the platform. Thus all of the pumps are driven p by'the'm'otor 113.

The solution circulating system of the apparatus is best shown in FIG. 10. Each pump is provided with a suction tube 114 and an outlet spout 115 which empties into the liquid in the tank desirably below the solution surface. The suction tubes 114 are extended and coupled to one of the ports in each of the units 91 as for example, the port 93 of each unit. The other ports 92 are connected to liquid conduits 116 extending thru the top of each tank and down into the solution to a point close to the bottom of the tank. If desired a check valve 117 may be inserted in each conduit 116 to prevent draining solution therefrom when flow therein is stopped.

Operation of the flow system is as follows. The pumps are operated constantly during the processing operation.

if no print is present to cover the slots 91 atmospheric pressure is maintained therein by flow of air thru the perforations in the apron 72. Therefore there is no fiow of liquid in the system because no reduction of pressure takes place in the liquid lifting conduits 116. When a print covers the slot 91 in any of the units 911 atmospheric pressure is excluded and pressure therein is reduced by the pump causing liquid to be drawn from the tank thru the conduit 116, laterally thru the slot, down the suction tube 114 and into the pump and is then discharged thru the spout 115 into the tank. When the print uncovers the slot 91 atmospheric pressure immediately is restored in the slot and circulation of solution stops even though the pumps continue to operate. Thus solutions are automatically applied to the printing sheet as it passes across the slot and such application automatically stopswhen the print has completed the travel across the slot.

It should be noted that the successful function of the novel processing system of the invention is due in part to the fact that the solution flow thru the slots 91 is motivated from the low pressure side of the pumps 103. As the print moves thru the processing station atmosq pheric pressure maintains its emulsion face in close contact with the peripheral edges of the slots 91 which provides a seal'against leakage of solution and since there is no positive pressure outward at this point leakage of solutions is practically eliminated.

When the print has traversed all of the processing units 919 it is completely processed and is carried by the apron '72 to the drying means 79 which consists of an enclosed chamber 118 one end of which is received between the side plates as and 67 and its other end extends to the left to a position where the completed and dried prints are discharged by the extended portion of the apron 72. Thus the path of the prints doubles back to a position close to their point of entry at the printing station. This structure greatly reduces the space occupied by the apparatus.

" The bottom wall of the chamber is perforatedand.

spaced a short distance from the apron 72. Its right hand end is curved to the contour of the apron. A plurality of electric heaters 119 are positioned at' intervals within the chamber'and connected to a suitable source of current as shown in FIG. ll.

Air under pressure is fed to the chamber and is heated by the'heaters 119. It then flows thru the perforations and upon the prints as they travel to the discharge point.

a A conduit 12% connects the discharge from the centrifugal blower 4b to the drier'79 thus the blower 40 provides a large flow of air under pressure to the drier and thru its connection 39 also provides vacuum for the chamber-38.

Power is supplied to the apparatus from source 121 as shown in PEG. 11. Each component may be provided With a suitable control switch not shown. The units 99 may be placed in operation by attaching coupling members 122 at the end of cables 1t12 to the respective double contact connectors 101. p a

The operation of the aparatus is very flexible with re- 7 spect to the quantity of light flux reaching the unit during exposure and also the timing ofthe development steps may be controlled within close limits to produce the highest possible quality in the finishing print or to produce special effects, department from normal processing pro operating voltage on the lamp 52 may be varied to provide up to 25% variation in intensity.- The distance from the lamp to the exposing slot may be varied. Neutral density filters may be inserted in the path of light reaching the exposing slot. To accomplish the latter control an additional filter wheel maybe received within the lamp housing to carry a series 'of neutral filters of varying density. As pointed out hereinbefore the width of the exposing slot may be changed by changing the interchangeable plates 66. In addition to this method the slot width may be changed by a suitable manual adjusting mechanism.

T 0 further adapt the apparatus to various requirements the processing time cycle is varied by varying the speed of travel of the. apron 72'which is accomplished by adjusting the speed changing unit 89 until the desired optimum is achieved. This facility provides for the use of different types of printing emulsions and also for different types and concentrations of developing and other processing solutions.

' In the above connection the mechanism for adjusting the slot width may be mechanically coupled to the speed control means on the speed changing units 89. This coupling means should be so constructed that the change in slot width would automatically change the processing time 7 to provide optimum quality in the finished print.

It should be noted in the use of the apparatus that processing time cycles may be held to a certain schedule and compensation in processing required by changes in exposure time or other factors may be achieved by adopting the well known two bath developing technique wherein the proportions of the ingredients in each bath may be varied to achieve the required adaptation to produce optimum results without a correction in processing time. Such a processing technique also permits the two conveying aprons 18 and 72 to operate at the same speed, which is -a desirable condition, even though by conventional developing techniques the two aprons should operate at different speeds when compensation is required to produce optimum results. I

Operation of the apparatus with the aprons traveling at difierent speeds is however a practical procedure. When the apron '72 is traveling faster than the apron 18 the bite between the apron '72 and the tires 70, when the print .to be processed first enters the processing station, is sufficiently firm to overcome the relatively light friction imposed upon the print at this time by the suction of the chamber 38 holding it against the apron 18. Having 9 entered the processing station the print is conveyed therethru at the speed of the apron 72. The roll 63 functions as a directional element in guiding the print at this point and exerts practically no friction holding back the print when its speed of travel is increased by the apron 72.

Since the same frictional forces are acting when the speed of the apron 18 is faster than that of apron 72 there will be slippage of the apron 18 upon the print when transfer from one apron to the other takes place. Since the driving friction of apron 18 is light there will be no damage to the print, which is dry at this time, and moreover it will not buckle or wrinkle since at this time the edges of the print are received in the guiding grooves of the members 45.

As explained above the processing units 90 are or may be adjusted peripherally of the discs 66 and 67 to present their slots 91 at dilferent distances along the path of travel of the prints. In this manner processing times may be varied.

As pointed out above the apparatus of the invention has wide scope in its operation and generally utility. In this connection it should be pointed out that contact reproductions may be produced from the smallest negative or other subject up to the maximum size capacity of the apparatus.

What is claimed is:

Apparatus for actinically exposing a photosensitive sheet through a transparent subject in sheet form in contact therewith comprising a light projecting means consisting of a fixed opaque lamp housing containing a lamp and having a transverse slot therein extending across the path of said sensitive sheet, a rotatably mounted hollow transparent cylinder encasing said housing, a conveyor apron engaging said cylinder, means to drive said conveyor and cylinder, said apron and cylinder acting to receive said sheet and subject therebetween and convey them over said slot to expose the sheet, said apron being extended substantially horizontally from said cylinder beyond said slot a distance at least as long as the sheet, a vacuum chamber substantially as long as the sheet having a flat perforated bottom wall extending close to the upper surface of said extension of the conveyor whereby said sensitive sheet is supported against the bottom face of said conveyor and transported thereby and said subject upon emerging from between conveyor and cylinder drops away from said sheet by gravity, delivering means engaging the forward edge of said sensitive sheet acting to direct it accurately into a predetermined plane for transport to another device having its receiving throat in line with said plane, a filter holding hollow cylinder having a plurality of filters thereon, means to rotatably mount said cylinder between said housing and said transparent cylinder and means to position a selected filter over said slot.

References Cited in the file of this patent UNITED STATES PATENTS 2,587,350 Maiwold Feb. 26, 1952 2,627,203 Hessert Feb. 3, 1953 2,719,714 Pratt Oct. 4, 1955 2,732,778 Limberger -Q. Jan. 31, 1956 2,766,044 Schulze Oct. 9, 1956 2,774,290 Mormann Dec. 18, 1956 2,783,697 Eisner Mar. 5, 1957 2,804,304 Taini Aug. 27, 1957 2,887,942 Frantz May 26, 1959 2,906,189 Robertson Sept. 29, 1959 

